NF-Kappa B is a transcription factor which regulates numerous inflammatory response genes. Cellular production of nitric oxide (NO) is increased in such inflammatory states. Depending upon the cell type, stimulus, concentration, and form of delivery, NO has been found to be either stimulatory or inhibitory to NF-Kappa B. This proposed research is designed to test the effects of NO or NO-related molecules on NF-Kappa B activity in the respiratory epithelium. Our preliminary studies indicate that NO has an inhibitory effect on NF-Kappa B in respiratory epithelial cells. The mechanism(s) by which NO exerts this effect is not understood. We hypothesize that NO regulates NF-Kappa B via the formation of a nitrosothiol on the p50-p65 heterodimer or another protein in the activation pathway. To investigate this hypothesis we plan to: 1. Determine the effects of exogenous and endogenous NO or NO-related molecules on NF-Kappa B activity in respiratory epithelial cells and determine whether these effects are sensitive to intracellular thiol levels. 2. Analyze recombinant NF-Kappa B proteins in vitro to determine whether they can be nitrosylated and at which site(s) this occurs on the molecule. 3. Determine whether these S-nitrosylated NF-Kappa B proteins are present intracellularly. 4. Determine the mechanism by which S-nitrosylation of these proteins alters their cellular function. The applicants long term goals are to become an independent investigator studying the regulation of gene transcription in the lung, in particular, as it relates to oxidative and nitrosative stress. With this award, the applicant will obtain the necessary training and experience in molecular biological techniques to achieve this goal.